| 摘要 |
An objective of the present invention is to diagnose a cavitation at a high precision without preparing for various types of pressure ratio tables against a variation of an installation environment (pipe layout) of a control valve. An upstream side fluid pressure (Pv1) and a downstream side fluid pressure (Pv2) of a throttle unit (axial flow unit) on the front and rear sides of a valve body in the control valve (101), and a fluid temperature (T) are detected. The downstream side fluid pressure (Pv2) is a fluid pressure at a fluid gathering part in a passage in the control valve (101). A pressure ratio (XFv) (XFv=(Pv2-Pv1)/(Pv1-Pv)) in the control valve (101) is calculated from a saturate vapor pressure of the fluid obtained from an upstream side fluid pressure (Pv1), a downstream side fluid pressure (Pv2), and a fluid temperature (T). A pressure ratio table (TB1) defining a relationship between a threshold value (XFvth) and a relative capacity coefficient (Cv) of the control valve (101)is written and stored in a memory unit (100-3) while taking a pressure ratio (XFv)[an initial value (XFvz)] in the control valve (101) when a cavitation starts to be generated in the control valve (101). Generation of the cavitation is determined by using the pressure ratio table (TB1). [Reference numerals] (100(100A,100B)) Cavitation diagnosing apparatus; (100-0) Saturated vapor pressure calculation unit; (100-1) Pressure ratio calculation unit; (100-2) Relative capacity coefficient calculation unit; (100-3) Pressure ratio table; (100-4) Determination unit; (100-5) Diagnosis result output unit; (TB1(TB2)) Memory unit |
